We have demonstrated a neurotrophic effect (i.e., prevention of the loss of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) from the preganglionically denervated superior cervical ganglion (SCG) of the cat) with homogenates of the central nervous system. The neurotrophic factor (NF) has been characterized as a heat-stable peptide at low (less than 1000) molecular weight. A similar neurotrophic effect has been found with glycyl glutamine, glycyl acid, and glutamic acid. Proposed research efforts will be directed toward: 1. Determination of the site and mechanism of action of endogenous and authentic NFs, and of continuous anesthesia with sodium pentobarbital in producing a similar effect. 2. Exploration of whether the NFs, under investigation may be involved in the control of components of the adrenergic nervous system. Accomplishment of any of the forgoing aims should result in increased understanding of the mechanism of neurotrophic action. These studies may also lead eventually to improvement in the treatment of brain and spinal cord injury and of Alzheimer's disease and other degenerative conditions of the central nervous system.